I kind of figured going all 30 inches across. But there'll be some kind of waterfall/pump going on there.
Your PM box is full now!PM'd you back, and yeah those guys are awesome.
For a skipper tank, you would have to go low end brackish. I'm not sure if Endlers would work in it, but I think guppies can go brackish. (I know mollies and platies can).
Your going to need a fair amount of land for them, you could do something similar to chrisinator's palu, where you divide land and water using sillicone and glass.
I'm really interested to see what you do with it, because I'm building the exact same type of set-up (37 with skippers)